The invention relates to a method for operating a navigation system in a vehicle and to a corresponding control system and a corresponding computer program product.
Vehicle navigation systems usually have the following components:
Routing
This component controls the planning of a route from a starting point to a destination via a plurality of possible waypoints.
Guidance
This component controls the guidance of the driver with respect to the planned route; this also includes the voice output of turn instructions, the display of arrows in a display device, for example a combination instrument or a head-up display. The guidance component ensures, in particular, that image representations of driving maneuvers, for example lane changes or turning, are provided for the different display media. The guidance component generally likewise directly ensures voice output.
Positioning
This component is used to control the positioning of the vehicle, for example using Global Positioning System (GPS) data.
Map Data
This component includes the map data and the handling and processing of said data. The latter may be stored locally in the vehicle. Map data may also be loaded into the vehicle navigation system from a storage medium or from an external source, for example a central data server, and possibly updated.
Map Viewer
This component is used to control the map display.
The present patent application relates, in particular, to the two components of map data and guidance. These components are generally very closely meshed. This is caused by the large volumes of data stored in the map. The amount of map and route data which need to be transmitted between the respective components for specific guidance to a destination is also generally relatively large. Therefore, on the basis of conventional bus systems with limited bandwidth, these data generally cannot be transmitted as a unit.
The object of the invention is to make it possible to efficiently transmit navigation data for operating a navigation system in a vehicle.
This and other objects are achieved by a method, control system and computer program provided in accordance with embodiments of the invention.
In order to operate a navigation system in a vehicle, a first aspect of the invention provides for navigation data from the navigation system to be transmitted to at least one of a plurality of control apparatuses of the vehicle. In this case, provision is also made for                the data to be transmitted via at least one data bus to which the control apparatuses are connected,        the navigation data to be prioritized, and for        the transmission of the navigation data via the data bus to be controlled on the basis of the prioritization.        
The invention may provide, in particular, for higher-priority data to be given preference over lower-priority navigation data during transmission, for example by way of a wider bandwidth provided on the at least one data bus and/or by way of shorter waiting times before transmission. A control apparatus may include, as control components, software components and/or electronic hardware components, in particular.
The invention is based on the knowledge that only a certain minimum throughput can be guaranteed on a data bus for transmitting route and map data, but free capacities on the bus can be used to achieve a higher throughput. It was also recognized that, for a guaranteed minimum throughput in bus systems, a predefined data volume or number of data frames can sometimes be reserved at regular intervals for an application. Prioritizing the navigation data makes it possible to at least partially reserve a minimum throughput for the prioritized data. The further available data volumes or data frames can then be used for other applications and/or lower-priority data.
The invention also recognized that it is possible to transmit complex or comprehensive navigation data with a dynamic bandwidth and with a relatively low guaranteed minimum throughput without having to effect a restriction to individual messages, that is to say selected related blocks of the navigation data. In the case of such a restriction which exists in conventional systems, simple messages are forwarded, for example in how many meters the next turning maneuver will be effected. The message catalog used in this case is very small and every new required event requires a change to the navigation system. Larger messages, for example relating to the route guidance, are normally transmitted only on request in such conventional systems. This means that every involved control component which requires this information must separately request it, which costs bandwidth, and must simultaneously be connected to the navigation system via a heavy-duty bus. In order to eliminate this problem and increase the available bandwidth, the present invention makes it possible, in particular, to achieve the situation in which the necessary map and route information is transmitted, together with data relating to the current position and/or speed, to all connected control components in a type of compressed form, with the result that an independent evaluation can be carried out in each connected control component. In this case, provision may be made, in particular, for the navigation data to be transmitted to a plurality of users and, in particular, to all users of the data bus(es) by broadcast.
A plurality of data buses may be provided, in particular, for transmitting the navigation data. In this case, a more powerful data bus, for example a Media Oriented Systems Transport (MOST) bus, can be provided for transmitting data between control components having higher data throughputs. In this case, control components may be components of the navigation system and/or of the respective control apparatuses of the vehicle. A less powerful data bus, for example a Controller Area Network (CAN) bus, may be provided for transmitting data between control components with lower data throughputs. An Ethernet network connection may also be provided as the data bus. The type of control may remain the same for the various data buses. The control component which respectively distributes the data can be started several times, for example if the storage sizes for connected devices differ. For example, control components which need to know only a few maneuvers, in particular only the next maneuver, within a predefined period and/or until the next maneuver message and accordingly can store only a few maneuver messages, in particular only one maneuver message, can be connected to a CAN bus. Conversely, a higher limit and/or an unlimited number of messages which can be transmitted and/or stored in a control component may be provided for a more powerful data bus, for example a MOST data bus. This function can be provided, in terms of programming, by instantiating the control component for data forwarding, for example. In this case, there is no need, in particular, to specifically configure which messages are intended to be transmitted.
In particular, the prioritization according to the invention of the navigation data makes it possible for these data to be interchanged between different control apparatuses and, in particular, between their control program modules in a modular control system. This also makes it possible to provide an open system in which further control apparatuses or control program modules can be connected, for example via an open interface (Application Programming Interface, API), without adapting existing control apparatuses.
The invention also makes it possible to reduce the data volume for the navigation data to be transmitted via the data bus and to compress the data and, as a result, avoid overloading of the data bus. In particular, corresponding data compression can be enabled by using the following features:                Only a relatively small part of the map data is needed for the route guidance or the other scenarios, namely only those which are in the immediate vicinity of the route. Only details of junctions are substantially required.        Route data substantially comprise maneuver data relating to the maneuvers of turning, driving straight ahead, changing road and/or additional information relating to lanes, traffic signs, speed or road type, for example.        Events are all the more important, the more imminent they are. For example, the next 500 meters are more important than events in 200 kilometers.        For some scenarios, there is no need to guarantee that they are always available, that is to say that they are also available in emergency situations in which the bus load may be high and loading by low-priority processes is unfavorable, for example scenarios relating to the comparison of map data or the interchanging of update data with a central server or a telematics module.        The data relating to the route can be hierarchically organized along different axes, for example according to up-to-dateness, level of detail, for example number of lanes at a junction, inscriptions on traffic signs, etc.        No GPS position is required for route tracking; the route can be represented as a linear section, in particular, and the current position along the route can then be coded using a single number, in which case a special, predefined number can be used to indicate that the route has been left.        The route is relatively static and changes only when the driver leaves the route or a traffic event makes replanning necessary. In the first case, the route changes, in particular, only locally at the currently traveled location but not further away; in the second case, the route changes, in particular, further away, possibly even the entire route.        
The invention makes it possible to provide for the navigation data to be provided in machine-readable form. In this context, machine-readable means, in particular, a sequence of binary-coded data or text in the Extensible Markup Language (XML) format or a corresponding electronically readable, in particular non-proprietary data format.
The navigation data may include, in particular, one or more sets of the following data:                type of a maneuver (turning, driving onto a freeway, taking an exit, etc.),        distance to the maneuver and/or position of the maneuver (for example coded as GPS coordinates),        lane in which the maneuver can be carried out,        general description of the roads involved at the location of the maneuver (what type of road, what maximum speed, how many lanes, what exits before and after, what type of intersection, etc.),        a representation of the type of intersection which is coded as vector graphics and can be adapted by display devices, in particular in the case of complex road courses,        information relating to additional displays (road signs, place names, direction arrows) which point in the direction of the maneuver or in the other directions.        
It may be useful to transmit or output a plurality of these sets when a plurality of maneuvers closely follow one another, for example.
According to one advantageous exemplary embodiment of the invention, data relating to the current geographical position and relating to the current speed are given a higher priority than maneuver data and geographical data relating to a route.
According to another advantageous exemplary embodiment of the invention, a minimum throughput is reserved on the data bus for transmitting the navigation data, and the minimum throughput is used to transmit the data in the prioritization order. In this case, the minimum turnover corresponds to a predefined data volume or a number of data frames within a predefined time window and is newly allocated on the data bus at regular intervals of time. The following high-priority navigation data or navigation messages may be provided, in particular, for the minimum throughput, a navigation message comprising a plurality of items of navigation data, in particular:                current geographical position, in particular current GPS position,        current speed, and/or        current position with respect to a traveled route.        
The minimum throughput may contain a predefined maximum data volume for low-priority navigation data and/or navigation messages which are assigned a lower priority than the high-priority navigation data. For example, a maximum of two elements in the form of low-priority messages may be provided. A priority value may be allocated to an entire navigation message and then applies to all navigation data in this navigation message. Accordingly, provision may be made for low-priority navigation data or messages to be transmitted on the data bus(es) only if there is sufficient bandwidth available.
A low-priority navigation message may comprise a plurality of partial messages with the following contents:                current relative position within a stipulated route in a geographical distance dimension,        type of maneuver at the current position, and/or        further information relating to the current position and/or relating to its environment.        
Low-priority navigation data may be, in particular, route data which can be processed as follows:                route parts which have already been traveled through are independently deleted by the connected control devices,        only changes and route parts which have not yet been transmitted are transmitted,        navigation data which relate to an earlier position on the route have priority over data with a lower position,        parts of the route which have not been changed are transmitted again only when more than a particular number of bytes have been transmitted since their last transmission, and/or        the data relating to the next maneuver are always concomitantly transmitted with the minimum throughput if this maneuver has not already been carried out and/or if the distance to this maneuver is shorter than a particular number of meters.        
In one advantageous embodiment of the invention, the navigation data are output only once to the at least one data bus and/or a further data bus by the navigation system within a predefined output time window. The navigation data can be output to the data bus(es) in the order of their assigned hierarchy within the output time window. At least one of the control apparatuses of the vehicle connected to the data bus(es) can store the navigation data output only once to the data bus(es) within the output time window for a predefined period and/or in a list with a limited storage size.
Navigation data generated in succession may be stored, in particular, in a navigation data list and the control apparatuses and/or control program modules may retrieve the navigation data. This makes it possible for a queue of the maneuver information to be provided and to be regularly queried by control components, that is to say so-called polling is carried out.
When outputting the navigation data, the navigation system may output, in particular, a report stating that data have been output. In this case, reference data relating to control apparatuses and/or control program modules may be stored or may have been stored in an output list. The navigation system can then use the reference data to inform the respective control apparatuses and/or control program modules of the respective output of the navigation data. The corresponding notification report can be effected using a communication means, in particular physically using the data bus(es), by means of a logical connection and/or by activating (so-called triggering) the respective control apparatus. A corresponding list of control program modules involved can be determined at the runtime or the compiler time. The control apparatus or its control program module can respectively wait for the trigger information (so-called listening). An activated control apparatus can access the navigation data, in particular after triggering. The navigation system can also forward maneuver information in machine-assessable form to other control systems of the vehicle without itself assessing the information beforehand. This makes it possible to further reduce the data volume to be transmitted. In addition, the security of the entire control process can be increased because, for example, the tasks the navigation system can be restricted substantially to navigation tasks and the entire control system, including the vehicle control apparatuses, can have a modular structure. This is advantageous, in particular, in a software-supported implementation.
The reference data may indicate, in particular, what type of navigation data (for example maneuver, position, etc.) are assigned to the respective control apparatus. The navigation data may be at least partially provided as category data, at least one of the following categories being provided:                an imminent driving maneuver,        a driving maneuver which has been carried out,        a measured value,        a report.        
The control apparatus may be connected, in particular, to at least one vehicle sensor which records vehicle states, for example a steering angle sensor and/or a speed sensor. Measurement data from the vehicle sensor can then be transmitted to the navigation system, in particular via the data bus(es). The positioning on the map, for example, can then be carried out using acquired vehicle data, for example steering angle and speed.
According to one advantageous exemplary embodiment of the invention, the guidance component is connected to at least one vehicle sensor directly and/or via the data bus. It is therefore possible, in particular,                to output a warning if proposed driving maneuvers (turning maneuvers, etc.) are not carried out or are not carried out in good time,        to compare map data such as signposts (turning instructions, place-name signs, street names) and speed limits with the actual conditions if detected by the vehicle sensor, for example using a camera mounted on the vehicle,        to inform vehicles in the surrounding area and/or a back-end server of imminent driving maneuvers via possible wireless car-to-car or car-to-X connections,        to automatically operate turn signals and the steering wheel and, in particular, to autonomously drive the vehicle,        to evaluate information relating to the temporal coordination of driving maneuvers for an alertness assistant of the vehicle,        to report deviations of the map data to a back-end server,        to carry out adjustments for people with disabilities or, for example, with age-related restrictions or according to individual wishes without changing the navigation system, for example to indicate a maneuver using more conspicuous indications and/or earlier than usual. In addition, the indication may be effected on further displays (for example in the rear seat), maneuvers can be indicated using further indications (for example with lights inside the vehicle) and/or further acoustic and optical signals can be emitted during particular maneuvers, and/or        to automatically reduce the speed before turning maneuvers for an automatic cruise control (ACC) system.        
In another aspect of the invention which can be used together with or independently of the aspects of the invention described above, maneuver data for carrying out a driving maneuver at a maneuvering location are output by a navigation system. At least one vehicle sensor and position data provided by the navigation system are used to check, even before reaching the maneuvering location, whether the maneuver has been initiated with the vehicle. A report is output if the maneuver has not been initiated.
In another aspect of the invention which can be used together with or independently of the aspects of the invention described above, maneuver data for carrying out a driving maneuver at a maneuvering location are output by a navigation system. At least one vehicle sensor, for example a camera, and position data provided by the navigation system are used to check whether navigation data stored in the navigation system, for example signs pointing the way, match corresponding data recorded by the vehicle sensor in the vehicle environment. The navigation data are adapted to the recorded data, in particular in the navigation system and/or in a central back-end server which can be connected to the latter via a mobile radio connection for example, if there is a discrepancy.
In another aspect of the invention which can likewise be used together with or independently of the aspects of the invention described above, a control apparatus of a vehicle is connected to at least one vehicle actuator which changes a vehicle state, for example an ACC actuator, and/or to a graphical, acoustic and/or haptic data output device of the vehicle, for example a combination instrument, a steering wheel vibrator, a car-to-car transmitter/receiver, a telematics system and/or, in particular, a mobile radio card. Maneuver data for carrying out a driving maneuver at a maneuvering location can be output by the navigation system, and position data provided by the navigation system can be used to output control signals to the vehicle actuator.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.